We begin with the trial of a Michigan man charged with murdering an unarmed teen on his porch. The prosecution expected to rest as early as today in this high-profile trial and ABC's Alex Perez brings us the latest from Detroit. Good morning, Alex. Reporter: Good morning. That's right, the prosecution is close to resting its case. Jurors heard testimony from a gun expert who says wafer had to know the gun was loaded. This morning, more evidence convicting Theodore wafer, the 55-year-old charged with fatally shooting 19-year-old renisha Mcbride, a gun expert testifying the story wafer told police he accide accidentally fired his shotgun is impossible. First needs to be loaded, that needs to be chambered and then the safety needs to be taken from safe to off. Reporter: In this dash cam audio recorded the morning of the incident wafer is heard telling an officer on scene he didn't know his gun was loaded. I didn't know there was a round in there. Reporter: A dispatch operator testified wafer told him the shooting was an accident. But defense attorneys arguing wafer intentionally fired the shotgun fearing for his own life when last November Mcbride ended up on his front porch drunk pounding on his door in the middle of the night. Prosecutors say Mcbride posed no threat to wafer arguing she was drunk and injured after crashing her car before the shooting. One expert testifying this spiderweb crack in the glass likely indicates Mcbride's head hit the windshield. May be possible for the driver to strike that windshield in some way, shape or fashion, giving those dynamics. Reporter: Wafer has pleaded not guilty but the big question remains, will he testify? Former prosecutor Todd flood believes the defense has no choice. He basically said he must take the stand Morad for the jury to believe him. There's nothing for them to believe anything in evidence of self-defense. Reporter: And we could know if wafer will take the stand very soon. Prosecutors are expected to call the medical examiner to wrap up their case today. Clearing the way for the defense to argue their side of all this. George. Okay, Alex. Thanks. Let's bring in our legal team, chief legal affairs anchor Dan Abrams and Nancy grace host of HLN's "Nancy grace". The prosecution has almost wrapped up. How have they done? In they've done an excellent job and there is recently been quite a skirmish in the courtroom too by the defense to try and allow in some selfies taken by the victim showing her partying suggesting that she was out of line that night, that's not going to come in. The judge has disallowed it and this is why. I had a case like this very early on when I was prosecuting where the defense tries to argue that the aggressor, in this case, the young girl, had a reputation for violence and here they're trying to say she was basically a mini thug. Well, unless the defendant knows of that reputation and then goes foo his thinking, wow, I've got to pull my gun and shoot, she's going to kill me then that is irrelevant in the case and the judge has just ruled on that. The defense has had two somewhat contradictory defenses. That's the problem here is on the one hand it's self-defense and on the other hand it seems to be a mistake and those are at odds. Self-defense means I intentionally shot someone because I was in reasonable fear for my safety and my life and I felt it was necessary to do it. But that's not what he's arguing here, it seem, at least. So far it seems the defense is going to say, it was self-defense up to the point of when he fired the weapon. Meaning he goes and gets his weapon, he prepares himself and all of this by the way is legitimate, right here, someone knocking on the door. The question becomes on the firing of the weapon, it sounds like he's saying, no, not self-defense, but it was a mistake. Meaning it was an dental discharge. Tough to argue both of those things at the same time. Nancy, where is the defense on stronger ground? Excuse me? Where is the defense on stronger ground? Oh, well, I think the defense is in a very bad position. What they're going to be claiming is that he was so afraid of this aggressor that he opened the door and fired. I think the only way to get any ground, any traction at all and I would never do this if I were the defense lawyer is to put him on the stand because he's going to be carved up like a Thanksgiving Turkey. I mean, come on. He says he couldn't find a cell phone but he could find his 12 gauge? And like the expert said, you got to load it, you got to cock it and take off the safety and it's a 6.5-pound trigger pull. So this was no accident. He's changing stories and FYI, if either of you two gentlemen end up in the backseat of a patrol car, hello, you're being recorded. Everything he said in that patrol car was recorded, it came into evidence and he basically said, hey, who knocks 0 your door at 4:30 in the morning? I shot her. He has to -- I'll make a note of that, by the way, Nancy, thank you. Note to self. Note to self. He has to testify. It's just -- there is no defense without him testifying in connection with this case. So without his testimony, there's nothing -- Dan, that's their only choice. That's right. It's thought a good choice but that's their only choice. That's it and, look, if I'm the defense in this case I'm shooting to -- shooting, so to speak, to find one or two jurors who will say, you know what, I think a reasonable person in that situation might have done the same thing. Go for a hung jury. They've got one other choice. They can attack the state. They can say, sloppy police work. That's into the going to work in this case. Come look at the door in it may not but when you don't have a choice, you got to go for anything. In does race come into play here? Race -- Nothing on the front door, nothing on the side door, nothing. No mark, not even a dent. So you asked about race coming into play. The bottom line is race will not be mentioned in the courtroom and yet every single juror you have to believe will be thinking about it so as a technical legal matter, race isn't an issue, shouldn't be an issue and yet as a practical matter there's no question that race is going to come into play both in terms of the jury makeup and what's going through their minds as they're evaluating the case in thanks very much.

This transcript has been automatically generated and may not be 100% accurate.

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